1. Field of the Invention
The invention relates to a gear pump for oil for an internal-combustion engine, in particular for motor vehicles, comprising a pump housing mounted on the motor, an outer rotor arranged in the pump housing, an inner rotor arranged in the outer rotor or the pump housing, at least one suction passage and/or at least one pressure passage in the pump housing, and a drive.
2. Description of the Prior Art
Pumps of this type are employed in a great variety of technical fields. However, gear pumps of this type are being increasingly used for internal-combustion engines, in particular motor vehicle internal-combustion engines, usually piston engines. For this purpose, the crankshaft is extended at its free end to drive the inner rotor or outer rotor. The inner rotor or driven outer rotor may be driven directly by the free end of the crankshaft. However, constructional forms are also known in which the inner rotor is located on a separate bearing collar formed in the housing of the pump. The collar is traversed by the crankshaft and driven via a catch.
As can be the case in the pump of the present invention, the flow direction extends in a feed passage approximately tangentially to the average peripheral direction of the pump gears in the so-called suction kidney area. Accordingly, the projection of the flow direction in the feed passage at the start of the area in which said passage merges into the suction kidneys, i.e. in the region of the inlet opening of the working chamber, onto a plane normal to the pump axis has a direction which substantially coincides with the movement direction of the teeth of the inner rotor and/or outer rotor in said region.
As also possible in the pump of the present invention, in the known oil pumps the feed passage, which at the connection of the oil suction tube may have the same circular cross-section as said oil suction tube, extends with tapering circular cross-section up to the beginning of the suction kidney. From there, the oil feed passage extends partially in front of the end wall of the working chamber and partially over the peripheral surface of the working chamber. The oil flow therefore flows not only around the end face of the outer rotor but also over part of the peripheral surface of the outer rotor. The suction kidney, i.e. the region of the opening of the working chamber, also extends over the end wall and the periphery thereof.
On the other hand, it is possible to choose a configuration for the suction kidney with which the oil flow no longer comes into contact with the peripheral surface of the outer rotor. Here, the arrangement of the suction kidney is provided only in one end wall of the working chamber.
However, in the prior art only gear pumps or internal rotor gear pumps for oil for motor vehicle internal-combustion engines are known which are provided as separate pumps and must be also separately driven.
However, this necessarily involves branching off drive energy from the engines connected to the known pumps, resulting in power losses. Also, additional space must be provided for the oil pumps.